Electronic components such as integrated circuits are found ubiquitously in modern consumer and industrial products. Many electronic components are sensitive to interference from electromagnetic (EM) radiation, or EM interference (EMI), particularly, though not exclusively, from radio frequency (RF) radiation. EMI can cause an electronic component to malfunction, which can cause the device in which the component is included to fail. Sources of EM radiation may include other nearby electronic components in the same device or sources external to the device.
Consequently, some form of EM shielding is needed for many common electronic components. Typical EM shields are structures that include a metal housing manually soldered onto pads on a circuit board. The metal housing encloses the sensitive electronic components, and the pads are electrically grounded. As such, the EM shield creates a Faraday cage around the sensitive electronic component(s). This EM shield can protect sensitive circuitry from a myriad of signals generated close to and remote from the sensitive circuitry.
The metal housing typically used for EM shielding is a bulky metal structure designed specifically for circuit board designs. As such, each circuit board design requires a uniquely sourced and designed EM shield, which can add to the cost of the product. Further, the metal housing can be difficult to solder onto pads of a circuit board. Moreover, the shield adds weight and volume to the product in which it is incorporated, which may be undesirable. Accordingly, existing EM shields have limited usefulness in electronic devices that are complex, portable, relatively small, and/or lightweight.
One approach to addressing these drawbacks includes forming a multilayer rigid shield over the sensitive electronic components by first pouring a liquid filler material over the sensitive components, allowing it to cool and solidify, and then pouring a liquid conductive material over the solid filler layer. The conductive material solidifies upon cooling to form a solid conductive layer, which is then electrically grounded. This multilayered structure forms a rigid EM shield that, unlike the bulkier metal housing, cannot be removed to repair or replace an enclosed electronic component. Other solutions include placing protective films over the sensitive electronic components. However, such films typically provide inadequate EM shielding.